Cattle tolerate short-term feed shortages far better than water shortages. Even mild water restriction rapidly reduces feed intake, rumen function, milk production and liveweight gain.
Warm weather amplifies water issues, with demand increasing sharply during the recent hot spell.
Typical summer water demand is 70-150 litres/day for lactating dairy cows, 40-70 litres/day for suckler cows and 30-60 litres/day for growing cattle.
A trough reserve of seven litres/cow is advised, ie a 700l trough for 100 cows.
Requirements increase further with warm weather, higher milk yield, lush, high-protein grass, walking distance and mineral supplementation.
Flow rate is as important as trough size.
Slow refill rates are often an issue.
Cows can drink 14 litres per minute, while the recommended flow rate for a 100-cow herd is 15 litres/minute.
Slow refill rates result in dominant cows getting their required water while timid cows are left waiting on water, cows bunching around the trough, leading to reduced intake across the group.
Many grazing herds have adequate trough capacity, but inadequate flow rates.
Reduced water access lowers dry matter intake and can lead to lower milk solids, poor thrive, reduced growth, poorer fertility and increased acidosis risk. Distance to water also affects grazing behaviour, reducing grazing time and pasture utilisation.
Bulls and calves are often overlooked.
Breeding bulls have high water requirements in summer and reduced intake may affect fertility.
Recently weaned calves may struggle with troughs, reducing thrive.
Trough height is important and a balance between ease of access and badger proofing is necessary. Dirty drinkers also reduce intake.
Biofilm, algae and faecal contamination reduce palatability and increase bacterial load which can cause issues.
Clean troughs frequently, check refill speed, ensure adequate trough size, avoid long walks to water and provide extra access during warm weather.
Marie-Louise Ryan, XLVets, Mulcair Vets
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